So I went to look at some sleeping bags today and the lady there said that you are supposed to get a bag that has at least 3-5 inches of free space at the bottom of the bag. She said having the extra space will make the bag warmer. I'm about exactly 6 feet tall and tried a 6 foot bag and I thought it fit pretty good with maybe an inch or two of space beyond my toes. The lady said I should go with the next size up though which is a 6'6" bag. Is that correct? If I go with that bigger one, I'll have probably 8 inches of bag beyond my feet. Sooooooo, how much extra space do you guys like to have past your feet?